The present invention relates to a vehicle electronic portable key system including an electronic portable key that performs wireless communication.
A vehicle electronic portable key system unlocks the doors of a vehicle when a vehicle occupant carrying a portable device (electronic portable key) approaches the doors and permits starting of the engine when the occupant enters the passenger compartment. In the vehicle electronic portable key system, wireless communication is performed between the vehicle and the electronic portable key when the electronic portable key enters an area set outside the vehicle near the vehicle doors or inside the vehicle. The wireless communication compares and verifies an identification (ID) code stored in the electronic portable key with an ID code stored in the vehicle. When determined that the two ID codes are in conformance with each other, the vehicle doors are unlocked and starting of the engine is permitted. The vehicle electronic portable key system reduces manual operations performed by the vehicle occupant and improves vehicle convenience.
When the owner of a vehicle implementing the vehicle electronic portable key system uses valet parking service, the owner gives the electronic portable key to a third person, such as a hotel attendant. In such a case, the third person who is given the electronic portable key may, for example, unlock the trunk without permission from the owner and remove valuables from the trunk. Japanese Laid Open Patent Publication No. 2003-511588 describes technology for preventing such tampering of a vehicle.
The vehicle electronic portable key system of Japanese Laid Open Patent Publication No. 2003-511588 uses electronic portable keys, which include a master key and a sub-key. The sub-key is lent to a third person. The master key and the sub-key have different ID codes. When ID code verification is performed through wireless communication that takes place between the vehicle and an electronic portable key, the vehicle electronic portable key system prohibits unlocking of the trunk lid by a vehicle occupant if the ID code of the sub-key is verified. Since the trunk lid cannot be unlocked by the sub-key, tampering of the vehicle may be prevented.
However, the sub-key is used only when it is lent to a third person. Thus, there is a tendency for the sub-key being left in, for example, a glove box in the passenger compartment. When a person breaks into the vehicle and steals the sub-key, the person would be able to steal the vehicle.